The present invention relates to devices for the replacement of interverterbral disks damaged or destroyed by disease or trauma, and in particular, to a hollow prosthetic device and a method of forming a hollow prosthetic device having a fluid infusion port which is sealed to prevent leakage.
When intervertebral disks are damaged or destroyed by disease or trauma, total removal of the disk is often indicated. Reconstruction or replacement of the function performed by the lost disk may require the use of autografts or allografts to fuse the adjacent vertebrae together. A more complete and natural restoration of function is possible with the implantation of prosthetic intervertebral disks.
U.S. Pat. No. 5,514,180 discloses intervertebral prosthetic devices having fixed shapes for accommodating the defined surface contours of the vertebral endplates. The invention defines five morphological types of surfaces comprising a set of surfaces capable of accommodating the anatomy of most vertebral endplates. A method of digitizing the surface of a vertebral body to determine a specific shape of a vertebral endplate is also disclosed. Furthermore this invention also relates to such prosthetic devices incorporating osteoinductive material such as bone growth factors.
U.S. Patent No. discloses a method for replacing the nucleus pulposus of an intervertebral disk. The nucleus pulposus is removed and a flexible hollow prosthetic disk is inserted into the space defined by the annulus fibrosis. The prosthetic disk is then filled with a gel material.
U.S. Pat. No. 5,545,229 discloses an intervertebral disk spacer comprising a central core of soft elastomer approximating the size and shape of the nucleus pulposus, an outer ring of stiffer elastomeric material approximating the size and shape of the annulus fibrosis, and endplates of stiff material incorporating a mechanism for attachment to the adjacent bony vertebral bodies.
U.S. Pat. No. 4,863,477 discloses an intervertebral disk prosthesis molded in the shape of the natural disk. The replacement disk is molded of rubber or silicone rubber. The replacement disk is formed from two halves joined together to form a hollow interior. After the disk is implanted between two vertebrae, a fluid, such as saline, is injected into the hollow interior space.
Various techniques are know for forming hollow prostheses. A technique developed by the inventor of the present invention is disclosed in U.S. Pat. Nos. 5,376,323; 5,855,606 and 5,700,288. The technique disclosed in these patents utilizes room temperature vulcanizable silicone. Room temperature vulcanizable silicone compositions are described generally in U.S. Pat. Nos. 3,925,277 and 3,897,376. A technique for forming prosthetic devices having varying degrees of flexibility is disclosed in U.S. Pat. No. 4,735,754 to Buckner. This technique selectively removes silicone material from the device to form voids having the requisite degree of flexibility.
U.S. Pat. No. 5,314,478 discloses a prosthesis that may be used as a replacement for an intervertebral disk. The prosthesis is a composite of polyvinyl alcohol hydrogel and a ceramic or metallic porous body.
U.S. Pat. No. 5,824,093 discloses a prosthetic spinal disk comprising a jacket surrounding a hydrogel core that is allowed to hydrate to a predetermined volume.
U.S. Pat. No. 5,702,454 discloses a prosthetic implant for replacing a spinal disk. Support members are inserted into a cavity in the core of the intervertebral disk until the cavity is filled.
U.S. Pat. No. 3,867,728 discloses a prosthesis for spinal repair comprising a core element having a flat top and bottom surfaces. The core is made of elastic polymer and may be reinforced. A covering element secured to both flat surfaces provides a tissue ingrowth receptive material.
The limitations of the prior art are overcome by the present invention as described below.